Based on a leap in mortgages starting last quarter, the stock should fetch $186, she argues in a note issued this morning.

Goldman was up $7.31, or 5%, on the news at $149.18 in early afternoon trading.

Tuesday morning, Goldman will be in the news again when it is slated to report second-quarter earnings. Many analysts expect Goldman will exceed estimates.

That said, Whitney's estimates for Goldman seem overly optimistic. She's forecasting earnings per share of $4.65 for the quarter, compared to the average estimate of $3.48, and $20 a share this year compared to the consensus $13.

Whitney's argument, as she explained on television, is that "safe harbor" rules for mortgages that went into effect on May 20 are preventing investors from suing mortgage servicers, leaving servicers a free hand to restructure mortgages, boosting lending. She says it's a boon for large banks.

Interestingly enough, Goldman has no significant exposure to residential mortgages or any other substantial position in consumer credit, as William Blair analyst Mark Lane pointed out in a note to clients on June 29. What Goldman does have are commercial mortgage assets that are still deteriorating, to the tune of $1 billion in the second quarter, he estimates.

But making outsized predictions for Goldman is totally understandable. The company blew away estimates for its March first quarter, earning $3.39 per share compared to the average $1.65. So, guessing Goldman these days is admittedly a wild ride.

Two things are clear: This mortgage market isn't what it was in 2007, and Goldman can do just fine delivering against rather weak results a year ago and very dismal expectations of banks in general.

Mortgage originations peaked in late 2006, early 2007, and after a jump in rates from near zero at the end of last year, the latest data show a big pullback in applications and refinancings.

Mortgage applications in the latest survey were two-thirds lower than they were back in December, with the "market composite index," a measure of the volume of mortgage applications, falling to 493.1 in the week ending July 3, down from 1,245 back in mid-December.

For perspective, the index is half what it was at in mid-March.

Goldman, meanwhile, has been beating estimates, as it has very low hurdles to clear.

Net revenue, excluding interest expense, fell by more than 50% last year and consequently should be up 73% this year, while profit is expected to triple to $13.20 per share, according to consensus estimates.

Last year's second quarter saw revenue decline 7%, to $9.2 billion. All Goldman had to do last quarter was not grow revenue at all, quarter over quarter, to beat that.

Instead, analysts have been steadily raising their estimates for months. They now expect Goldman to deliver net revenue of $10.7 billion, an increase of 16%.

Betting on Goldman has of late been a winning strategy. The shares are up 19% since Goldman sold $5 billion worth of stock priced at $123 back on April 14.

This brings us back to mortgages. In mid-2007, the heyday of originations, Goldman stock traded at 2.4 times book value and had a return on equity of 27%.

These days, Goldman trades at just 1.6 times the $98 in book value most analysts are modeling, and those analysts are praising the company for what may be 18% return on equity last quarter, after buying back the government's TARP shares.

With expectations that low, you don't have to believe in very much at all to believe that in time Goldman shares can probably rise to two times book value, which is what Whitney's $186 price target represents.

You just have to believe Goldman's performance won't be as bad as most other banks, which is pretty much assured.